For producing wiring patterns on a semiconductor wafer, such a method is adopted that: a liniment called a resist is applied to the semiconductor wafer; an exposure mask (reticle) for the wiring patterns is superposed on the resist; visible rays, ultraviolet rays, or an electron beam is irradiated to the resultant resist in order to expose the resist to light for development; the wiring patterns of the resist are thus formed on the semiconductor wafer; and the wiring patterns of the resist are used as a mask to perform etching on the semiconductor wafer so as to form the wiring patterns.
For investigation of a mask or a pattern shape on a wafer, a critical dimension scanning electron microscope (CD-SEM) that is a type of scanning electron microscope is widely used. For evaluation of the pattern shape, coordinates at which SEM imaging is performed are called an evaluation point that is abbreviated to an EP. In order to image the EP with a small imaging deviation volume and with high image quality, part or all of adjustment points such as an addressing point (hereinafter, an AP), an autofocus point (hereinafter, an AF), an auto-stigma point (hereinafter, an AST), and an auto-brightness/contrast point (hereafter, an ABCC) are set if necessity. At the respective adjustment points, addressing, autofocusing, auto-stigma adjustment, or auto-brightness/contrast adjustment is carried out. Thereafter, the EP is imaged.
As for an imaging deviation volume in addressing, an SEM image at an AP which is registered in advance as a registration template and whose coordinates are known is matched against an SEM image observed in an actual imaging sequence, and a deviation volume in the matching is compensated as a deviation volume of an imaging position. The evaluation point (EP) and adjustment points (AP, AF, AST, and ABCC) shall be generically called imaging points. The size and coordinates of the EP, imaging conditions for the EP, the imaging conditions for the adjustment points, an imaging method, an imaging order (or an adjustment order) for the imaging points, and the registration template are managed as an imaging recipe. Based on the imaging recipe, the SEM images the EP.
In the past, an SEM operator has manually composed a recipe, and the work has been labor-intensive and time-consuming. For determining adjustment points or registering a registration template in a recipe, it is necessary to actually image a wafer at a low magnification. Composition of the recipe has become a factor for decreasing the working ratio of an SEM device. Further, along with a tendency toward finer and more complex patterns, the number of EPs requested to be evaluated has explosively increased. The manual composition of the recipe has become unrealistic from the viewpoints of labor and composition time.
A semiconductor inspection system in which: an AP is determined based on design information on semiconductor circuit patterns described in, for example, the GDS II format; and data at the AP is cut out from the design information, and registered in an imaging recipe as a registration template has been disclosed in Japanese Patent Laid-Open No. 2002-328015 (hereinafter, patent document 1). Herein, it is unnecessary to image an actual wafer only for the purpose of determining the AP and registering the registration template. The working ratio of an SEM improves. In addition, the semiconductor inspection system has such a function that: when an SEM image (actual imaging template) at the AP is acquired in an actual imaging sequence, the actual imaging template is matched against the registration template in the design information; the SEM image associated with the position of the registration template in the design information is re-registered as a registration template in the imaging recipe; and the registration template of the re-registered SEM image is employed in addressing processing. Further, the semiconductor inspection system has such a function that a characteristic pattern portion is automatically detected from the design information and registered as an AP.
Japanese Patent Laid-Open No. 2005-265424 (hereinafter, patent document 2) describes that an image obtained by imaging an addressing pattern at about a several-tens-of-thousands-fold magnification is compared with a preliminarily stored addressing template image in order to obtain the position of the addressing pattern; central coordinates of a length-measurement area are acquired based on the obtained positional information; and an enlarged image of a length-measurement position is acquired at a several hundred-of-thousands-fold magnification on the basis of the central coordinates information.
Further, Japanese Patent laid-Open No. 2007-250528 (hereinafter, patent document 3) describes, as a method for automatically composing an imaging recipe for use in imaging a specimen using an SEM, that coordinates of an EP, a size thereof, a shape thereof, imaging conditions therefor, and CAD data on the surroundings of the EP are inputted in order to compose the imaging recipe, which includes the number of imaging points for use in observing the EP, coordinates of the imaging points, sizes thereof, shapes thereof, an imaging sequence, and imaging conditions, in a wafer-less manner.
As an EP, a user-designated point, or a risky spot which is outputted from an electronic design automation (EDA) tool, which is called as a hot spot, and at which a device malfunction is likely to occur is cited. Based on a pattern dimension value at the EP, feedback is performed in order to correct the shape of a mask pattern or modify the conditions for a semiconductor fabrication process. Thus, a high yield is attained. In response to a need for a high speed and high integration of semiconductor devices, miniaturization and densification of wiring patterns has made progress and a super resolution exposure technology represented by optical proximity correction (OPC) has been introduced. Since mask patterns are getting more complex accordingly, prediction of simulation of pattern shapes to be transferred to a wafer or inspection of the actually transferred pattern shapes has become more important.